EP0146032B1 - Méthode et appareil pour la conversion d'un système de voltage polyphasé - Google Patents

Méthode et appareil pour la conversion d'un système de voltage polyphasé Download PDF

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EP0146032B1
EP0146032B1 EP84114357A EP84114357A EP0146032B1 EP 0146032 B1 EP0146032 B1 EP 0146032B1 EP 84114357 A EP84114357 A EP 84114357A EP 84114357 A EP84114357 A EP 84114357A EP 0146032 B1 EP0146032 B1 EP 0146032B1
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phase
input
output
frequency
amplitude
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EP0146032A2 (fr
EP0146032A3 (en
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Marco Venturini
Alberto Alesina
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
    • H02M5/02—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc
    • H02M5/04—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters
    • H02M5/22—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M5/25—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means
    • H02M5/27—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means for conversion of frequency
    • H02M5/271—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means for conversion of frequency from a three phase input voltage

Definitions

  • the present invention relates to a direct AC-AC frequency converter, i.e. a converter of electric energy able to convert a polyphase AC input supply into an equivalent polyphase AC (or possibly DC) output system with frequency, amplitude and phase independently controllable, without any intermediate conversion step through a DC system.
  • a direct AC-AC frequency converter i.e. a converter of electric energy able to convert a polyphase AC input supply into an equivalent polyphase AC (or possibly DC) output system with frequency, amplitude and phase independently controllable, without any intermediate conversion step through a DC system.
  • a power supply with a frequency and an amplitude that are different from those available such as the variable speed drive of induction or synchronous motors, by adjusting simultaneously both the frequency and the amplitude of the supply system, the constant frequency, variable speed generators (VSCF), whereby the variable frequency energy produced by the prime mover (typically an airplane turbine) is converted to constant frequency before use, etc.
  • VSCF constant frequency, variable speed generators
  • the use of higher than line, controlled frequency allows important advantages in the design of almost all electric machines.
  • frequency converters are known, which, for different reasons, do not fully provide the desirable features listed above.
  • existing frequency converters can be grouped into two categories: AC-DC-AC converters and direct converters.
  • the converters of the former type consist of two stages; in the first, the AC input is converted into an intermediate DC bus, which is in turn converted by the second stage into an output AC system with the desired properties.
  • the most common drawbacks of this type of machines are the generally unidirectional energy flow, the need for large reactive elements in the intermediate filter, and non-sinusoidal waveforms.
  • Direct converters synthetize the AC output directly out of t AC input without any intermediate stage. They consist of a number of switches connecting the input phases with the output phases in different combinations and of various types of filters.
  • the best known converter of this type are the cycloconverter, the UFC (Universal Frequency Changer) and SEC (Slow Frequency Changer) and the HSFC (High Speed Frequency Changer) disclosed by the first inventor in GB-A-2 048 588.
  • the output waveform is a piece-wise approximation of the desired sinusoid obtained by sampling the input phases once per input cycle, by means of a matrix of switches, and according to different control methods. Consequently, the quality of the output waveform can only be improved by increasing the number of the input phases, and of the switches, with obvious cost penalties.
  • the HFSC synthetizes the output waveforms by sequentially connecting all the input phases to any given output phase, at frequency substantially higher than both the input and the set output frequency, and by modulating the sampling time of each input phase proportionally to a suitable combination of two sinusoids, where such sinusoids have a frequency which is proportional to the sum of and to the difference between the set output frequency and the input frequency. Therefore, the output waveforms, and symmetrically the input waveforms, consist of a sinusoidal low frequency component, as measured with respect to the input neutral conductor, whose amplitude, frequency and phase are independently controllable, and of a cluster of high frequency harmonics, centered around and above the sampling frequency, and therefore easy to be filtered if necessary.
  • the input current is also sinusoidal and the relevent phase displacement is controllable but subject to the limitation that the absolute value of the input phase angle is less than or equal to the output phase angle.
  • the HSFC allows for a continuous and independent control of frequency, amplitude and phase; however, the output amplitude is intrinsecally limited to 0.5 times the input amplitude.
  • the switch matrix must be designed to withstand the full input voltage, this feature implies a non optimal use of the power semiconductors in the matrix.
  • the ratio between the trigonometric tangents of the input and output phase angles is limited to be no greater than 1 in module, which prevents the use of the converter in a number of applications related to reactive power compensation such as static VARs.
  • a further object of the invention is to realize a method for converting a polyphase balanced system into another one, more particularly a three phase system into a three phase system having different amplitude, frequency and/or phase angle.
  • the invention consists of a method for directly converting a three phase input voltage system, balanced and sinusoidal, having input amplitude v,, frequency w i /2 ⁇ and phase angle s,, into a three phase output voltage system, also balanced and sinusoidal, and having output voltage v o , frequency wo/2n and phase angle so wherein at least one of the latter quantities is different from the former, and each output waveform is obtained by sequentially sampling all the input phases and said sampling is carried out through nine modulation coefficients m k , h (t) expressing the ratios between the time that the input phase h is connected to the output phase k and the overall sampling period, whereby said modulation coefficients contain components at the frequencies 3w o ⁇ w, with the same amplitude; at the frequencies 2w, and 4w, the amplitudes of which are in a constant ratio of 7:1 and of opposite sign, and at frequencies w o ⁇ w, with the ratio of their amplitude being a function of tg(s l
  • the invention further consists in a method as above indicated in which the modulation coefficients are the entries of the following matrix: where: with:
  • the invention consists in a direct AC converter including three input phase conductors and a neutral conductor for a balanced three phase AC input voltage system, three output phase conductors and a neutral conductor for a three phase AC output voltage system having at least one characteristic such as frequency, amplitude, phase angle or phase displacement which is different from that of the input voltage system, the input and output neutral conductors being unconnected between them, the converter building up the output voltage through a 3x3 matrix of bidirectional electronic controlled switches subsequently connecting each output phase conductor with each input phase conductor, characterized by the fact that said switches are operated in accordance with the method.
  • Such frequency converter consists of a number of bidirectional electronic switches, which connect each input conductor with each output conductor, and which are operated at a substantially higher frequency (from 5 to 20 times) than both the input and the set output frequency, driven by a logic control circuit such that for each output phase, at any given time, one and only one switch is closed.
  • the control circuit drives the switches with variable duty cycle as will be detailed later on.
  • the direct converter shown in Figure 1 comprises two main portions, more precisely a plurality of controlled electronic switches SW1...SWS arranged to form a switch matrix MU, and a control circuit supplying the necessary control or drive signals to the switches, illustrated in the remaining portion of the drawing.
  • the converter is connected between a three phase input voltage system LI through a filter I, and a three phase output voltage system LU through a filter U.
  • the matrix MU consists of nine switches which connect any given input conductor with all output conductors. More generally, for polyphase systems with n input lines and m output lines, the switch matrix consists of nxm switches. Such switches must be adequate to withstand the maximum supply voltage as well as the maximum load current.
  • the corresponding output phase conductor can be connected with all the input conductors through the switches SW1, SW2, SW3 out of the SW1...SW9 switches of the matrix.
  • Such switches are cyclically operated, i.e. closed, at a frequency f c , where f c is substantially higher (e.g. 10 times) than the highest of both the input and output frequencies, and in such a way that at any time one and only one of SW1, SW2, SW3 is closed.
  • the cycle time 1/f o is very short, the three input voltages do not vary appreciably during the switching cycle.
  • m 11 (t), m 12 (t), m 13 (t) be the ratios between the time during which the output conductor (1) is connected to the corresponding input conductor (1, or 3) and the overall switching cycle T c , i.e. the duty cycles of SW1, SW2, SW3 within the cycle T.
  • V 11 , V 12 , V, 3 are the three input voltages during T c , as measured with respect to the neutral input conductor N, then the output waveform consists of three samples of the input voltages and will have an average amplitude, within T c , approximately equal to:
  • the output waveforms amplitudes as referenced to the input neutral conductor are the following: p being a parameter that will be defined later and comprised between zero and one.
  • phase to phase output voltages are: i.e. they are sinusoidal and with the correct phase relationships.
  • the waveforms represented in (1) allow for maximizing the output phase to phase voltages (2) without exceeding the fundamental limitation of this type of converter, with respect to the range of the input voltages.
  • any of the output voltages (e.g. V oi ) as measured between the corresponding phase conductor and the input neutral conductor, comprises the usual component at the desired output frequency (v o cos(w o (t)) with the proper phase angle, and a common term given by
  • This term is formed as a linear combination of two sinusoidal waveforms, the first one at a frequency that is three times the output frequency, and the second one at a frequency that is three times the input frequency.
  • the common term will be a linear combination of two sinusoidal waveforms, one having a frequency which is m times the output frequency, and the other having a frequency which is n times the input frequency.
  • the converter of the present invention is therefore capable of synthesizing waveforms of the type represented in (1).
  • Such waveforms are synthetized as follows:
  • each of the element mk,h(t) representing the duty cycle of the corresponding switch SW is formed by a linear combination of six sinusoidal terms (as given by relationship (3)).
  • Relationship (12) represents anyone of the three voltages of relationship (1) when using the compact notation given by (3).
  • Relationship (13) represents, with the same notation, the input current of phase h.
  • the ratio S between the trigonometrical tangents of the input and output phase displacements can be greater than 1 since this does not lead to values of the duty cycle, as expressed by mk,h(t), that are either negative or higher than 1. Therefore the controllable range of the input-output phase displacement is greatly enlarged.
  • control circuit capable of generating drive signals according to (6)...(11) is now described with reference to Figure 1.
  • Said control circuit converts the input control variables such as desired output frequency, amplitude and ratio between tangents of input and output phase displacement, into the appropriate drive signals for the power switches in MU.
  • the control circuit in its simplest form has four input control lines and nine output control lines.
  • the input control signals are the desired ratio between the output and input voltages v o /v i , the desired ratio tg(s,)/tg(s o ), the desired output frequency and the actual input frequency;
  • the output control signals are the drive pulses for the matrix MU.
  • said control circuit can be either an analog one ( Figure 1) or a digital one ( Figures 4A, 4B, 5A, 5B).
  • the output frequency is set through the circuit Q1 comprising a voltage source and a potentiometer.
  • a voltage controlled oscillator VC converts said voltage into an AC voltage having the frequency equal to the desired one (w o ) and an AC voltage having a frequency which is three times the former (3w o ).
  • the input frequency is sensed on LI, shaped and squared by filter F. With this signal, the phase locked loop PL7 generates two synchronous AC voltages with frequency two and four times the input frequency (2w, and 4w,).
  • phase locked loops PL1...PL6 are three phase, sinusoidal with controllable amplitude, and can be synchronized on the sum or the difference of two input frequencies.
  • the so obtained signal proportional to S is fed to a comparator C1 and a rectifier R1.
  • the output from R1 is therefore proportional to
  • circuit Q4 comprising a voltage source and a potentiometer.
  • the network comprising X1 and A1, a multiplier and an amplifier respectively, result in a signal proportional to a according to (8), while adder/amplifier A2 together with multiplier X2 provide a signal proportional to p according to (9).
  • This signal is fed to amplifiers A5, A6 to control the amplitudes of PL3, PL4, while its absolute value, obtained by rectifier R2, is used to control the amplitude_of PL5 and PL6 through amplifiers A7, A8.
  • the voltage gains of A5...A8 are proportional to
  • signal a and the value zero are fed to multiplexer M in direct and reverse sequence, M being controlled by C1 so that signals a 1 , a 2 according to (10) are available on the multiplexed outputs of M.
  • Such outputs are fed to adders A3, A4 together with signal p and the resulting outputs control PL1, PL2 amplitudes according to (6).
  • the eighteen signals provided by PL1...PL6 are proportional to the sinusoidal components which form the duty cycle coefficients m k , h (t) according to (6)...(11). These signals are combined, in the correct order, by adders S1...S9 which output signals, proportional to mk,h(t) as given by (11), also providing the fixed offset required by (6). Such outputs are converted into drive pulses by programmable timers T1...T9 whose output pulse durations are proportional to the amplitude fed at the programming input.
  • the timers are connected in rings of three units, where each group is connected to a single output line, in such a way that the end of each timer cycle would trigger the start of the next timer.
  • Timer outputs are decoupled and amplified by driver circuits D1...D9 which drive the power switches SW1...SW9 in the power switch matrix.
  • the converter can be completed by optional input and output filters I and U, capacitive and inductive respectively, which may be required with high impedance supply or with non-inductive loads.
  • a digital processor is used to compute and evaluate the numerical values of matrix (11) at regular intervals, much shorter anyway than the duration of both input and output cycles. For example, in an application where both input and output frequencies are below 100 Hz, the matrix M(t) can be evaluated once every millisecond.
  • the program of the processor consists of an initialization routine ( Figure 4A) which upon processor start up or on interrupt whenever the control parameters are changed, inputs the values of w,, w o , v,, v o , S and evaluates constants a,, a 2 , p according to (8) (9) (10).
  • Two subroutines ( Figures 4B, 5A) can be defined to simplify the main program. The first one ( Figure 4B) generates the function ZO(y)(t) as defined by (3) whereas the second one ( Figure 5A) generates function m(x 1 ,...,x 6 ) as defined by (6). After the execution of the control is returned to the main program.
  • the processor timer updates the time register t, and evaluates M(t) with the mentioned subroutines.
  • the nine numbers thus obtained are then fed to digital to time duration converters or down counters, which drive in sequence, through driver circuits, the nine power switches in MU as described before.
  • the power switches which form MU can be realized in many already known ways, for example as described in the cited U.S. Patent, or with newer components such as bidirectional power MOSFETs or COMFETs.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Ac-Ac Conversion (AREA)

Claims (3)

1. Procédé pour convertir directement un système de tension à entrée triphasée, balancé et sinusoïdal ayant une amplitude d'entrée v,, une fréquence wi/2π et un angle de phase s,, dans un système de tension à sortie triphasée, lui aussi balancé et sinusoïdal et ayant un voltage de sortie vo, une fréquence wo/2π et un angle de phase so dans lequel au moins une des dernières quantités est différente des précédentes, et chacune forme d'onde de sortie est obtenue en échantillonnant en séquence toutes les phases d'entrée et ledit échantillonnage est obtenu au moyen de neuf coefficients de modulation mk.h(t) exprimant le rapport entre le temps pendant lequel la phase d'entrée h est reliée à la phase k de sortie et la période totale d'échantillonnage, où lesdits coefficients de modulation contiennent des composants ayant des fréquences 3wo±w, avec la même amplitude, ayant fréquences 2w, et 4w, les amplitudes desquels sont en un rapport constant de 7:1 et de signe opposé, et de fréquences wo±w, avec le rapport de leur amplitude étant une fonction de tg(s,)/tg(so).
2. Procédé ainsi que revendiqué dans la revendication 1), caractérisé par le fait que lesdits coefficients de modulation sont les suivants:
Figure imgb0040
où:
Figure imgb0041
avec
Figure imgb0042
Figure imgb0043
Figure imgb0044
Figure imgb0045
Figure imgb0046
3. Convertisseur direct de courant alternatif comprenant trois conducteurs de phase d'entrée et un conducteur neutre pour un système de tension d'entré triphasé balancé de courant alternatif, trois conducteurs de phase de sortie et un conducteur neutre pour le système de tension de sortie triphasé ayant au moins un caractéristique telle que la fréquence, l'amplitude, l'angle de phase ou de déplacement de phase lequel est différrent duquel de l'entrée du système de tension, les conducteurs neutres de l'entrée et de la sortie étant pas reliés entre eux, le convertisseur réalisant la tension de sortie au moyens d'une matrice de 3x3 interrupteurs bidirectionals commandés éléctroniquement lesquels relient en succession chacun conducteur de phase de sortie avec chacun conducteur de phase d'entré, charactérisé par des moyens pour activer lesdits interrupteurs en accord avec le procédé des revendications 1) ou 2).
EP84114357A 1983-12-05 1984-11-26 Méthode et appareil pour la conversion d'un système de voltage polyphasé Expired EP0146032B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT2400883 1983-12-05
IT24008/83A IT1167285B (it) 1983-12-05 1983-12-05 Metodo e apparecchiatura per la conversione di un sistema di tensioni polifase

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EP0146032A2 EP0146032A2 (fr) 1985-06-26
EP0146032A3 EP0146032A3 (en) 1985-08-28
EP0146032B1 true EP0146032B1 (fr) 1988-07-06

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3285386A1 (fr) 2016-08-10 2018-02-21 Phase Motion Control S.p.A. Convertisseur courant alternatif/courant alternatif direct à matrice

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US5101899A (en) * 1989-12-14 1992-04-07 International Royal & Oil Company Recovery of petroleum by electro-mechanical vibration
US5747972A (en) * 1995-01-11 1998-05-05 Microplanet Ltd. Method and apparatus for electronic power control
US7315151B2 (en) * 1995-01-11 2008-01-01 Microplanet Inc. Method and apparatus for electronic power control
US6328102B1 (en) 1995-12-01 2001-12-11 John C. Dean Method and apparatus for piezoelectric transport
US5909367A (en) * 1997-06-02 1999-06-01 Reliance Electric Industrial Company Modular AC-AC variable voltage and variable frequency power conveter system and control
US6995992B2 (en) * 2003-06-20 2006-02-07 Wisconsin Alumni Research Foundation Dual bridge matrix converter
US6982890B2 (en) * 2003-10-09 2006-01-03 Wisconsin Alumni Research Foundation Three phase isolated vector switching AC to AC frequency converters
DE102004004369A1 (de) * 2004-01-29 2005-08-18 Jungheinrich Ag Batterieladegerät
DE102004016464A1 (de) * 2004-03-31 2005-11-03 Alstom Technology Ltd Verfahren zur Berechnung und Beurteilung des Frequenzspektrums eines Matrix-Konverters

Citations (1)

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EP0124302A2 (fr) * 1983-04-06 1984-11-07 Texas Instruments Incorporated Convertisseur d'alimentation à courant alternatif

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CA826777A (en) * 1959-07-06 1969-11-04 F. Blake Richard Controlled frequency power supply system
US3170107A (en) * 1960-05-02 1965-02-16 Westinghouse Electric Corp Controlled frequency alternating current system
US3585489A (en) * 1969-06-20 1971-06-15 Westinghouse Electric Corp A low-frequency ac reference generator with inherently balanced controllable output voltage
US3999112A (en) * 1975-05-08 1976-12-21 Westinghouse Electric Corporation Polyphase frequency converter
US4041368A (en) * 1976-01-02 1977-08-09 Borg-Warner Corporation Three-phase, quasi-square wave VSCF induction generator system
IT1111993B (it) * 1979-03-06 1986-01-13 Venturini Marco Convertitore di frequenza diretto ca/ca
US4352155A (en) * 1981-08-14 1982-09-28 Westinghouse Electric Corp. Variable speed constant frequency power converter with two modes of operation
US4439823A (en) * 1982-01-11 1984-03-27 Westinghouse Electric Corp. Converting multiphase power from one frequency to another using current waveforms
GB2113485A (en) * 1982-01-13 1983-08-03 Texas Instruments Ltd An a.c. supply converter

Patent Citations (1)

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Publication number Priority date Publication date Assignee Title
EP0124302A2 (fr) * 1983-04-06 1984-11-07 Texas Instruments Incorporated Convertisseur d'alimentation à courant alternatif

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3285386A1 (fr) 2016-08-10 2018-02-21 Phase Motion Control S.p.A. Convertisseur courant alternatif/courant alternatif direct à matrice

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IT1167285B (it) 1987-05-13
US4628425A (en) 1986-12-09
EP0146032A2 (fr) 1985-06-26
EP0146032A3 (en) 1985-08-28
IT8324008A0 (it) 1983-12-05
DE3472605D1 (en) 1988-08-11

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